Analysts said the ruling signalled new uncertainty for East Africa’s most developed economy. Another vote must be held within 60 days, according to the constitution.

The main stock index, the NSE-20, dropped 3.5 percent to close at 3887.28 points, data from the Nairobi Securities Exchange showed.

In London one Africa economist, John Ashbourne at Capital Economics, cited the risk of a violent reaction.

President Uhuru Kenyatta said he disagreed with a Supreme Court ruling that nullified his win in last month’s presidential election, but that he would respect the decision and urged citizens to do the same.

There were also no signs of tension in Kenyatta’s ethnic strongholds, while supporters of opposition leader Raila Odinga celebrated peacefully in the streets in areas that had voted for him.

“People will be looking at the tone the president takes,” Ashbourne added.

Kenya has a history of disputed elections. A row over the 2007 poll, in which Odinga also lost out, was followed by weeks of ethnic bloodshed in which more than 1,200 were killed. ($1 = 103.1500 Kenyan shillings) (Additional reporting by Alexander Winning and John Ndiso; editing by Larry King)